Research On Wind-induced Vibration Control Of Bridge Tower In Construction Period Based On New PTMD

Strong wind has great influence on the construction safety and operation safety of longspan bridges.It is one of the important factors to be considered in design and construction.The span of modern cable-stayed bridges and suspension bridges is getting larger and larger,and the height of bridge towers is bound to become higher and higher..However,the bridge tower is a flexible structure,and wind is its main load.The increasing height of bridge towers will inevitably increase the intensity of the wind load.In the state of bridge formation,the bridge tower has less response to the wind due to the cable support of the bridge.However,the wind load has a great influence on the bridge tower during the construction process.Long-term structural vibration and structural vibration with excessive amplitude will cause fatigue or even damage to the structure of the bridge tower,resulting in serious economic losses,threatening the comfort of the construction workers and even life safety.Therefore,the vibration control problem of the bridge tower in the construction stage is becoming more and more important.At present,the wind resistance of the bridge mainly adopts three types of bridge wind resistance measures,namely pneumatic measures,mechanical measures and structural measures..Mechanical measures are a widely used solution.The tuned mass damper(TMD)is a mechanical damping control method used to suppress wind-induced vibration.Based on the predecessors,a new pounding-type tuned mass damper(PTMD)with collision boundary is designed.Through the model experiment and numerical simulation of the vibration damping control of "L" shaped flexible rod as the pilot research,the damping control performance of the new PTMD is analyzed,and the damping control effect of the new PTMD on the buffeting of the bridge tower is studied.The specific research work is as follows:(1)A steel model with a simple structure but high flexibility of "L" shaped was fabricated,and a PTMD model was made for the model.The model experiment in which the two work together was used as a pilot study to test the new PTMD’s damping control effect on the "L" shaped flexible rod under different working conditions.(2)The experimental structure-PTMD coupling model is established in Matlab,the working conditions in the experiment are simulated,the calculation results are fitted with the experimental results,and the relevant parameters of PTMD are determined to further verify the effectiveness of PTMD vibration control under different working conditions.The influence law of different parameters on the vibration control effect of the new PTMD is explored,and the optimal parameter value is established.(3)According to the harmonic superposition method,the bridge tower buffeting is simulated.The simulation program of the buffeting wind field corresponding to the Sutong bridge tower is established by Matlab,and the time-domain simulation of the buffeting excitation of the bridge tower is carried out.The finite element model of the self-supporting Sutong bridge tower was established by ANSYS.The self-vibration characteristics were analyzed and the stiffness matrix of the pontic vibration was extracted.A new type of PTMD specially designed for bridge tower damping control is designed.The coupling model of Sutong Bridge-PTMD was established by Matlab/Simulink.The vibration damping control effect of the new PTMD on the bridge tower was calculated and analyzed.